Scientists observing asteroid 2015 TB145 with NASA’s Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii, say it is probably a dead comet that has shed its volatiles after numerous passes around the sun.

‘The IRTF data may indicate that the object might be a dead comet, but in the Arecibo images it appears to have donned a skull costume for its Halloween flyby,’ said Kelly Fast, of Nasa.